Sounds like dogs to me. I' m not sure why but a dog will eat the butt right out of a deer every time. I have no idea how it died. Maybe got hit by a car and ran to where you found it. A lot of times when a deer gets hit by a car there is are no visible injuries but run off to die from internal injuries. Since you said this was in a residential area my guess is that dogs are what chewed on it.